Electric storage battery

ABSTRACT

Electrode plate for an electric storage battery including a lug for electrically coupling the plate to other plates in the battery and an insulating collar tightly engaging the root of each plate lug. In a stack of plates, the several collars abut one another so as to separate the lugs from each other and may serve to form a mold for shaping a plate strap cast thereon.

This invention relates to plates (i.e., electrodes) and cell elementsfor electric storage batteries.

BACKGROUND OF THE INVENTION

Electric storage batteries (e.g., lead-acid, Ni-Zn, etc.) compriseseveral galvanic cell elements each immersed in an electrolyte andencased in separate compartments of a substantially leak-proofcontainer. Each cell element comprises at least one plate-like, positiveelectrode (i.e., a positive plate), one plate-like negative electrode(i.e., negative plate) and a porous separator (e.g., a thin microporoussheet and/or absorbent glass mat) therebetween. Multi-plate cellelements are commonplace and comprise a stack of alternating positiveand negative polarity plates interleaved one with the other and theseparators. The plates themselves each comprise a conductive substratewhich supports an electrochemically active material thereon and conductselectrical current substantially uniformly therethrough. In Pb-acidbatteries, for example, the plates comprise a leady active material(i.e., PbO₂ for the positive plates and Pb for the negative plates)pasted onto a reticulated Pb-alloy grid substrate. A lug projects fromthe substrate/grid of each plate and serves to electrically couple theplate to other electrical components (e.g., terminals, other plates,etc.) of the battery. One such coupling occurs between aligned lugs oflike polarity plates within a multi-plate cell element and thence, viaan intercell connector, to opposite polarity plates in adjacent cells.In some instances, the lugs are coupled by simply bundling and weldingthe plates lugs together through an aperture in an intercell partitionof the container such as shown in FIG. 5 of U.S. Pat. No. 4,046,062tomatter. More typically, however, the several plate lugs are electricallycoupled one to the other by a bus bar, known as a plate strap, which isburned to, or cast about, the plate lugs: (1) inside the batterycontainer such as disclosed in FIG. 2 of the aforesaid U.S. Pat. No.4,046,0672; or (2) outside the battery container such, for example, asdisclosed in Eberle U.S. Pat. No. 3,841,915 where the plate strap isformed in the container's cover.

It has been proposed to position preformed strips of insulating materialover the lugs of each set of aligned positive or negative plate lugs(e.g., see U.S. Pat. No. 2,287,802) to facilitate manufacturing, torigidify the stack, and/or to prevent accidental internal shortcircuiting of the cell. Likewise, it has been proposed to fit apreformed trough over the plate lugs to form a mold for forming acast-in-place plate strap onto the plate lugs and through the intercellpartition (e.g., see U.S. Pat. No. 3,988,169). Finally, our owncopending U.S. Pat. application Ser. No. 783,359 filed Oct. 3, 1985entitled "Electric Storage Battery", which is incorporated herein byreference, discloses pressure molding a strip of plastic in and aboutthe roots of aligned plate lugs to tightly engage the lugs and to firmlyhold them in precise alignment with, and spaced from, each other. Thislatter approach to providing a plastic strip on the roots of the lugsrequires stocking a variety of different molds in order to accommodatecell elements having different numbers and thicknesses of plates.

There exists a need for an even better way for providing a strip ofinsulating material about the plate lugs of a cell element. Moreover,there exists a need for a way to provide a leak-tight seal between theplate lug(s) and an external wall of the battery container.

Accordingly, it is an object of the present invention to facilitatebattery assembly by providing the lug(s) of each battery plate with itsown individual, tight-fitting, insulating collar which mates: withsimilar collars on other lugs to form a segmented insulating strip atthe roots thereof; with similar collars on other lugs to form a mold forforming a plate strap about the plate lugs; and/or with an aperture in acontainer wall to facilitate the formation of a substantiallyliquid-tight seal therewith. It is a more specific object of the presentinvention to provide a galvanic cell element having a segmented strip ofinsulating material about its plate lugs, which strip comprises aplurality of discrete lug collars in aligned abutting relation one tothe other. These and other objects and advantages of the presentinvention will become more readily apparent from the detaileddescription thereof which follows.

BRIEF DESCRIPTION OF THE INVENTION

The present invention comprehends a battery plate having: a conductivesubstrate supporting an electrochemically active material; a lugprojecting from the substrate to electrically couple the plate to otherelectrical component(s) (e.g., plates, terminals, etc.) of the battery;and a discrete, insulating collar formed tightly about the root (i.e.,proximate the substrate) of each lug, which collar is adapted to engagecollars on other lugs, and/or an aperture in the battery's containerwall forming a substantially liquid-tight seal therewith or otherwise tofacilitate various battery assembly operations.

According to a preferred embodiment of the invention, a battery cellelement is formed from a plurality of lug-bearing, positive and negativepolarity plates alternately interleaved with one another wherein eachplate lug has a discrete insulating (e.g., thermoplastic orthermosetting resin) collar formed about the root thereof (i.e., nearthe plate's active material). The collar on each lug is aligned inabutting relation to other collars on other lugs of like polarity platesin the element and together therewith serve (1) to space the severallugs apart, (2) to insulate the lug's electrical connector from platesof opposite polarity, and (3) in some instances to form a mold forforming a plate strap, in situ, about the plate lugs. The distal end(i.e., remote from the active material) of each lug engages anelectrical connector (e.g., plate strap) which electrically couples theseveral plate lugs together. Each collar will most preferably have aU-shaped configuration, the legs of which extend up along the edges ofthe distal portion of its associated lug and, when aligned and abuttedto other collars, forms a trough for shaping a plate strap moldedtherein.

In accordance with another aspect of the present invention, the severalcollars may be tied together by means of a thread, or the like,extending the length of the aligned collars through apertures formedtherein. The thread will be bonded (e.g., welded) at its ends to the endcollars in each stack.

In accordance with another aspect of the present invention, the U-shapedcollars are provided with laterally extending flanges for engagingportions of a container wall surrounding an aperture in the wall intowhich the collar has been fitted. A sealant applied to the flanges andthe wall seals the collar in the aperture.

DETAILED DESCRIPTION OF THE INVENTION

The invention may better be understood by reference to the followingdetailed description of certain specific embodiments thereof which isgiven hereafter in conjunction with the several figures in which:

FIG. 1 is a perspective view of a cell element having aligned, abuttingU-shaped, plate-lug collars in accordance with the present invention;

FIG. 2 is a section in the direction 2--2 of FIG. 1;

FIG. 3 is a section taken in the direction 3--3 of FIG. 1;

FIG. 4 illustrates one method of assembling a battery element havingplate-lug collars in accordance with the present invention;

FIG. 5 is a perspective view of a battery container adapted to receivecell elements assembled as indicated in FIGS. 4 or 7;

FIG. 6 is a perspective view of a portion of the battery container ofFIG. 5 having cell elements made in accordance with the presentinvention inserted therein;

FIG. 7 illustrates another method of assembling a battery cell elementhaving plate-lug collars in accordance with the present invention;

FIG. 8 is a perspective view of another method of assembling a batterycell having plate-lug collars in accordance with the present invention;

FIG. 9 is a perspective view of the battery cell after assemblyaccording to the technique illustrated in FIG. 8; and

FIG. 10 is a perspective view of a portion of a battery assembled inaccordance with another embodiment of the present invention.

FIG. 1 depicts a battery cell element 1 comprising a stack of positiveplates 3 interleaved with a plurality of negative plates 5 andappropriate interplate separators (not shown). The plates comprise anactive material 7 supported on a conductive substrate, here shown as agridwork of wires 9 joined at the top by a header 11. A plate lug 13projects from each positive plate 3 and is aligned with other positiveplate lugs along one side (e.g., the top) of the cell element stack 1.The negative polarity plates 5 have similar plate lugs 15 thereonsimilarly aligned. A U-shaped insulating collar 17 is firmly secured tothe root (i.e., adjacent the header 11) of each positive plate lug 13and is aligned in abutting relation with similar collars on the alignedlugs 13. Similar collars 19 on the negative lugs 15 are similarlyaligned. While the following description is given in conjunction withthe positive plates and their associated lugs and collars, it is to beunderstood that the substantial content thereof applies equally to thenegative plates and associated lugs/collars. The collars space thealigned lugs from each other and preferably comprise a thermoplasticmaterial (e.g., polypropylene, polyphenylene sulfide, or the like)injection molded directly about the lugs. The collars 17 preferably havea U-shaped configuration including a base portion 21 engaging the root23 of each lug and upstanding legs 25 which flank the lateral edges 27of the distal portions 29 of the lugs which are more remote from theactive material 7 of the plate. The U-shaped collars 17, when alignedwith similar collars, form a trough 31 for receiving an appropriatecoupler, e.g., cast-in-place plate strap (not shown), for electricallyjoining the distal portions 29 of the several lugs together. In the caseof a cast-in-place plate strap, the trough 31 serves as a mold to shapethe molten lead cast therein. End plates 33 are provided at the ends ofeach trough 31 opposite the end where the intercell connector is to beformed and serve to prevent molten lead from spilling out of the end ofthe trough 31.

Each plate lug collar 17 and end plate 33 has an aperture 35 (i.e.,about 0.065 inch diameter) formed therethrough to facilitate tying theseveral aligned lugs together in the stack. In this regard, when theseveral collars 17 are aligned, the apertures 35 line up as best shownin FIGS. 2 and 3. A thread 37 (e.g., 0.063 diameter polypropylene) isinserted through the several apertures 35 and has its ends 39 and 41heat staked (e.g., headed over by a hot knife) to the end collar/endplate to tie the several collars 17 tightly together.

FIG. 4 depicts another method of assembling a Pb-acid battery utilizingplate-lug collars in accordance with the present invention. According tothis method, a plurality of positive plates 43 are stacked together(i.e., interleaved with negative plates, not shown) to form one cellelement stack 45. Similarly, a plurality of negative plates 47 arestacked together (i.e., interleaved with positive plates, not shown) toform another cell element 49. The two cell elements 45 and 49 aredestined for placement in adjacent cell compartments of a batterycontainer after being electrically joined together via an intercellconnector insert 51. The lugs 53 of the positive plates 43 of stack 45have polypropylene collars 55 injection molded about the roots 57thereof leaving the distal portions 59 thereof disposed above thecollars 55 for electrical coupling to each other by an appropriate means(e.g., plate strap). Similarly, a plurality of negative plates 47 havetheir lugs 61 provided with collars 63 and are stacked together (i.e.,interleaved with positive plates, not shown) to form the cell elementstack 49. The cell elements 45 and 49 are positioned in an appropriatefixture or jig (not shown) so that the positive plate lugs 53 of element45, the negative plate lugs 61 of element 49 and the intercell connectorinsert 51 are positioned as shown. The intercell connector insert 51comprises an intercell connector element 65 which bridges an intercellpartition of the container and flanges 67 and 69 on the opposite ends ofthe element 65. A steel mold 71 is then placed over the aligned lugs andinsert. The mold 71 has a first molding cavity 73 encompassing thedistal ends 75 of the negative plate lugs 61 and a second molding cavity77 encompassing the distal ends 59 of the positive plate lugs 53 at thesame time. The aligned and abutting lug collars 55, 63 form the bottomsof the mold cavities 73 and 77. Molten lead introduced into the moldcavities 73, 77 melts and fuses to the distal portions 75 and 59 of thelugs 61 and 53, respectively, as well as to the outer faces of theflanges 67 and 69 of the insert 51. The molten lead essentiallysolidifies into plate straps 79 and 81 and joins the lugs and inserttogether in a unified assembly which is ready for insertion into anappropriate battery container 83 (see FIG. 5).

The assembly formed as described in conjunction with FIG. 4 is insertedinto a battery container 83 which includes a plurality of intercellpartitions 85 for separating the several cell compartments one from theother. Each partition 85 includes a slot 87 adapted to receive theintercell connector element 65 in the manner shown in FIG. 6. Ribs 89are provided on the partition 85 adjacent the slot 87 and serve toengage the inside faces 91 of the flanges 67 and 69 of the intercellconnector insert 51. The lower ends of the ribs 89 engage a shelf 93formed (i.e., in a second molding operation) at the bottom of the slot87 and together therewith define a cavity 99. During assembly, the cellelements 45 and 49 are positioned in adjacent cell compartments 95 and97 of the container 83 such that the inside faces 91 of the insert 51engage the ribs 89 and shelf 93 to enclose the sides of the cavity 99.Thereafter an injection molding mold (not shown) is positioned over thepartition 85 so as to encompass the slot 87 and flanges 67 and 69.Thermoplastic container material (e.g., polypropylene) is then injectedinto the mold so as: to fill the cavity 99; seal the connector element65 in the slot and envelop the peripheral edges 101 of the flanges 67and 69; and fill the remainder of the slot 87 above the cavity 99 to thetop of the partition 85.

FIG. 7 depicts another similar method of assembling a battery utilizingthe lug collars of the present invention. Cell elements 103 and 105 haveplastic collars 107 and 109 molded about the roots of their respectiveplate lugs 111 and 113. The lugs sets are aligned with an intercellconnector insert 115 in the same manner as described in conjunction withFIG. 4. In this embodiment, however, U-shaped pieces 117 and 119 oflead-coated copper are positioned about the lugs 111 and 113. Thereaftera steel mold 121 is positioned about the pieces 117, 119 and insert 115.Molten lead is then introduced between the legs 123 and 123' of theU-shaped pieces 117 and 119 to join the insert 115, plate lugs 111 and113 and U-shaped pieces 117 and 119 together into a single unit 125.Thereafter the mold 121 is removed and the cell elements 103 and 105positioned in a battery container in the manner as described inconjunction with FIG. 6.

Another application of plate-lug collars in accordance with the presentinvention involves forming the battery's interplate and/or intercellconnectors and/or terminals on the outside of the battery container suchas, for example, as shown in FIGS. 8 and 9. A battery cell element 126is formed by interleaving a plurality of negative plates 127 with aplurality of positive plates 129 and intercell separators 131essentially as described above. In the particular form shown, eachnegative plate 127 and positive plate 129 will have two lugs 133 and135, respectively, for more efficient conduction of current to and fromthe plate. Individual insulating collars 137 are molded about eachnegative plate lug 133. Similarly, individual insulating collars 139 aremolded about the positive plate lugs 135. Each collars 137 and 139 has agenerally U-shaped configuration including a base portion 141, legs 143and two sets A and B of flanges 145--145' and 147--147' which extendlaterally outwardly from the legs 143. The flange sets A and B definetherebetween openings 149 and 151 which mate with a portion of theexterior wall of a battery container as will be described in more detailhereinafter. A battery container comprises a plurality of discrete trays153 which nest one within the other. The trays 153 each include slots155 and 157 in the external walls 159 thereof for receiving the lugcollars 137 and 139, respectively, as depicted. The flanges of theflange sets A and B embrace the portions of the container wall 159forming the edges of the slots 155 and 157 which are snugly received inthe openings 149 and 151 between the flanges. When so positioned, thecollars 137 and 139 fill and substantially plug the slots with whichthey are mated. Thereafter molten lead is cast about the lugs betweenthe legs 143 of the aligned collars 137 and 139 to form plate straps 161in essentially the same manner as discussed above. In some instances,the container tray 153 will be the end tray in a stack and hence housethe end cell of the battery. In such instances, a battery terminal 163may be provided as follows. In this regard, several of the legs 143 areremoved from the center region 165 of the aligned collars. The ends of aPb-coated copper strap 167 are fitted into the openings 165 in thecenter region and molten lead cast between the legs 143 of the alignedcollars to fuse the ends of the strap 167 to the plate straps 161 at thetime of their formation. A stud 169 projects from the strap 167 forattachment to external circuitry. After the molten lead has solidified,the region about the connections is enclosed within a mold and hotplastic 170 injected thereabout to seal the collars within theirrespective slots and otherwise to put the connection in plastic, asshown in phantom in FIG. 9.

FIG. 10 depicts a variation of the structure shown in FIG. 8 wherein alug collar 171 includes a single pair of oppositely extending flanges173 and 175 lying contiguous the container wall 177 and sealed theretoby plastic 179 molded thereabout.

While the invention has been described in terms of certain specificembodiments thereof it is not intended to be limited thereto but ratheronly to the extent set forth hereafter in the claims which follow.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. In a galvanic cellincluding a stack of positive and negative polarity, lug-bearing platesalternately interleaved with one another and means for electricallyjoining aligned plate lugs into sets of like polarity, the improvementcomprising:said lugs each having a root portion proximate said plate anda distal portion more remote from said plate and engaging said means; adiscrete, insulating collar tightly surrounding said root portion ofeach said lug; and the collars of said aligned lugs abutting one anotherso as to space said aligned lugs apart and to insulate said joiningmeans from the plates of opposite polarity.
 2. A cell according to claim1 wherein said collars each have a generally U-shaped configuration andsaid aligned abutting collars together define a trough for molding saidjoining means.
 3. A cell according to claim 1 including means for tyingsaid collars together in said aligned abutting relationship.
 4. A cellaccording to claim 3 wherein said collars each have at least oneaperture formed therethrough in a direction substantially perpendicularto the plane of the lug, the aperture of each said collar being alignedwith apertures of the other collars when aligned in said abuttingrelationship and together defining a passageway therethrough and saidtying means comprises a thread extending the length of said passagewayand secured at each end to the end collars in the stack.
 5. A cellaccording to claim 4 wherein said thread comprises a thermoplasticmaterial, the ends of which are, heat staked to said end collars.
 6. Inan electric storage battery comprising a container having a plurality ofwalls defining an enclosure for a galvanic cell, an aperture in at leastone of said walls, a stack of positive and negative polarity,lug-bearing plates alternately interleaved with one another housedwithin said container, and means for electrically joining aligned platelugs into sets of like polarity, the improvement comprising:said lugseach having a root portion proximate said plate and a distal portionmore remote from said plate and engaging said means; a discrete,insulating collar tightly surrounding said root portion of each saidlug; the collars of said aligned lugs abutting one another within saidaperture so as to space said aligned lugs apart and to substantiallyfill said aperture; and means bonding said abutting collars insubstantially leak-proof fashion to said wall adjacent said aperture. 7.A battery according to claim 6 wherein each said collar has a generallyU-shaped configuration having its legs extending along either side ofthe distal portion of its associated lug and together with said abuttingcollars defining a trough for molding said joining means.
 8. Amulti-cell electric storage battery comprising: a container having aplurality of walls defining a plurality of individual cell compartments;a galvanic cell housed within each said compartment, said cellcomprising a stack of positive and negative polarity plates alternatelyinterleaved one with the other; an aperture in at least one of saidwalls; a lug projecting from each of said plates and through saidaperture, said lug being aligned with similar lugs projecting from likepolarity plates of one said stack for electrically joining said likepolarity plates to plates of opposite polarity in another said stack inthe next adjacent cell compartment; a discrete, insulating collartightly surrounding each said lug where it passes through said aperture,said collar abutting a similar collar on at least one of said alignedlugs so as to space said aligned lugs apart and substantially fill saidaperture; and means bonding said abutting collars in substantiallyleak-proof fashion to a portion of said wall adjacent said aperture. 9.A battery according to claim 8 wherein each said collar includes towsets of substantially parallel flanges, said sets extending in oppositedirections from each other substantially normal to the lateral edges ofthe lug, the flanges of each said set defining therebetween an openingfor receiving said portion.
 10. An electrode plate for an electricstorage battery comprising: a conductive substrate supporting anelectrochemically active material thereon; a lug projecting from saidsubstrate for electrically coupling said plate to other component(s) ofsaid battery; and an insulating collar molded in situ about said lug andadapted to mate with an aperture in a wall of the battery's container,said collar including at least two flange portions each extending inopposite directions one from the other substantially normal to thelateral edges of said lug for sealing to such portion of said wall asdefines said aperture.
 11. An electrode according to claim 10 whereinsaid collar includes at least four of said flanges arranged in sets oftwo wherein the flanges of each set are substantially parallel to eachother and define therebetween an opening for receiving said portions.12. A multi-cell electric storage battery comprising: a container havinga plurality of walls defining a plurality of individual cellcompartments; a galvanic cell housed within each said compartment, saidcell comprising a stack of positive and negative polarity platesalternately interleaved one with the other; an aperture in at least oneof said walls; a lug projecting from each of said plates and throughsaid aperture, said lug being aligned with similar lugs projecting fromlike polarity plates of one said stack for electrically joining saidlike polarity plates to a terminal of the battery; a discrete,insulating collar tightly surrounding each said lug where it passesthrough said aperture, said collar abutting a similar collar on at leastone of said aligned lugs so as to space said aligned lugs apart andsubstantially fill said aperture; and means bonding said abuttingcollars in substantially leak-proof fashion to a portion of said walladjacent said aperture.